مجله پژوهش آب ایران
پیاپی 32 (بهار 1398)

Population growth affects the need of communities for crops. No country is excluded from this rule. Cotton is one of the strategic products in Iran. Increasing the cultivating of this crop reduces the country's need for importing. On the other hand, water scarcity has caused human societies to seek solutions to eliminate the consequences of this issue. One of these methods is to find the exact relationship between the amount of water and fertilizers consuming and product yield. In other words, the amount of yield achieved per unit of consumed water and fertilizer is considered. Knowledge about these relationships can help improve water and fertilizers management. Iran is one of the countries that despite the increase in population growth water resources are reducing day by day. Therefore, it is necessary to determine the exact relationship between water and fertilizer units and cotton yield. This test was a step towards optimizing and improving management. Therefore, the results of this experiment can be used to answer questions related to water-fertilizer relations and yield. In order to evaluate the cotton yield response to the combined effect of water consumption and fertilizer use, an experiment was conducted in 2012 at Hashem Abad Station in Gorgan, Iran. The experiment was carried out with six water levels of 0% (in the case of dry or without irrigation), 36%, 66%, 88%, 100%, 132% of water requirements, and four fertilizer levels of 0%, 33%, 66% and 100% of fertilizer requirement, and Two cotton cultivars of Golestan and B 557 were carried out in the form of strip split plot with three replications. Treatments of fertilizer and cultivars were selected in strip and perpendicular to irrigation strips and these strips were randomly placed in each replicate. From the collision of these strips perpendicularly, plots with dimensions of 2.5 × 3 m were created. Cotton cultivation was carried out on May 25, 2012, at a distance of 25 centimeters and a row spacing of 75 centimeters. There were 4 planting lines in each plot. Among these, two marginal and two midline lines were considered for yield measurement. In this experiment, the soil was tested before planting and the texture, salinity, alkalinity, and fertility needs of the farm were determined. Sprinkler irrigation method was applied by linear system. Spray sprinkler radius was 12.5 meters and the sprinkler spacing was 6 meters. Before irrigation, the moisture content of the soil was tested by weight. Irrigation time was determined based on soil moisture content, sampling the second strip (5W). The duration of irrigation was calculated based on the required depth to field capacity and the intensity of spraying in the second strip (5W). During the cropping period, the moisture content in the base treatment was in terms of crop capacity, except for the two cases provided by irrigation. Irrigation was carried out in the quiet hours of the night due to the calmness of weather conditions and the reduction of winding and evaporation losses. Before sunrise, the amount of irrigation water was measured by canisters in the middle of each plot. Fertilizer was provided manually in two stages: 40% fertilizer requirement of each plot before planting, and 60% after planting and before flowering. Plant yield was obtained from the first and second harvest. Functional weight included fiber and cotton seed. In order to determine the best production function, simple linear function, logarithmic and quadratic regression were used and the results were evaluated and assessed. The evaluation of the results of fitting the logarithmic yield function of Golestan cultivar showed that the statistical characteristics of RMSE, R2, EF and ME respectively were equal to 0.12, 0.86, 0.007 and 0.33. Comparison of statistical characteristics of linear and quadratic functions with logarithmic function revealed that the logarithmic function for different values of water-fertilizer simulates the yield of Golestan cultivar more precisely. On the other hand, the quadratic equation was selected as the weakest production function in Golestan cultivar, with values of RMSE, R2, EF and ME equal to 0.55, 0.73, 0.09 and 0.61, respectively. These results for the B-557, despite the change in the different values of the indices, had similar results with Golestan cultivar. Water use efficiency for Golestan cultivar and B 557 was obtained in W3 treatment (36% water requirement) and W1 (0% water requirement, dry farming and cultivation without irrigation), which indicated Golestan cultivar had higher water use efficiency than B-557

Bottom intakes are frequently used as diversion structures for small hydro-electric power plants, agricultural and industrial uses in mountainous regions, because of their simplicity and their low costs in comparison with the other methods of river intakes. Also, Bottom intakes have the minor changes and little circumstances on river morphology, comparing with the other measures of extraction of water from rivers. The flow passing through the bottom intakes is categorized as spatially varied flow in which the discharge is decreased along the canal. Major studies on the performance of bottom intakes were conducted on experimental models. In experimental models, the study is focused on the discharge deviation due to ensemble of the racks. For determining the efficient parameters which influence the process, some extra studies on the flow characteristics are needed. The measurement of all flow characteristics could not be done in laboratory. Hence, a calibrated mathematical model permits to determine certain parameters which could not be measured in a physical model. In this study, the Flow3D software was utilized to simulate the current passing through the bottom racks in an experimental model. Firstly, the mathematical model was calibrated. The mesh size and the adequate turbulence model were investigated to assess the maximum similitude between experimental and numerical model for the discharge deviated by racks. Among 5 different turbulence models (including 1 equation model, standard k-ɛ model, k-ε RNG model, Prandtle's mixing length model and LES model), the k-ε RNG model provided more accurate results by evaluating the parameters of determination. MAE=0.18, RMSE=0.36 and R2=0.98 were obtained for k-ε RNG model. The numerical model by different mesh size (2, 4 and 8 millimeters) was built and the discharges deviated by racks in numerical model were compared with ones in experimental model. The numerical models built by 2mm and 4mm cells sizes provided the results very close to experiments, while 8mm cell size exhibited the considerable different results. Considering the time costs for numerical models, the model with 4 mm mesh size was selected as the most convenient model. For the next simulations, the meshes with 4 mm in their sizes were selected. Following the calibration of numerical model, the racks with eight different cross sectional geometries are simulated by the numerical model. The ordinary racks' geometries (oval, circular, lozenge and rectangular) and the hybrid geometries (circular and triangular, circular and rectangular) were modeled by numerical method. For each model, the diverted discharge, velocity, pressure distribution around the racks and also the velocity profile of the outlet discharge along the racks were compared with each other. Finally, according to the results, three geometry, circular, lozenges and the combination of the two later sections were compared in terms of efficiency and performance. The maximum deviated discharge was considered as the parameter for comparing the performance of each category. The maximum diverted discharge ratio belonged to triangular superimposed on semicircular, semicircular superimposed on triangular and lozenge category, with 58.25%, 56.78% and 56.68%, respectively. Although the category of triangular superimposed on semicircular category was more efficient in discharge deviation, the velocity distribution along the racks was not uniform. The pressure distribution and the differences between the maximum and minimum pressure were considered as the indicators for evaluating the performances of each category. The hybrid cross section with triangular superimposed on semicircular exhibited more uniform pressure distribution along the racks and the maximum differences between the maximum and minimum pressure occurred above and under the racks. These conditions conduct to the ability of this category in discharging the water. The results provided in this paper were applied for the clear water. We propose to evaluate the performances of racks in the presence of sediment. Especially, for certain shapes of racks, the sediment might be trapped between racks and influence the performance of trash racks. Further researches are needed for the water transporting the sediments. In this research, the hydraulic of collector was not studied. The performance of collector under different conditions subjected to the shapes of racks could be as a domain of research. The hydraulic of collector is influenced by the flow distribution along the racks. The less uniform for the water arrived to the collector, the more complexity in hydraulics of collector is expected.

Due to the uncertainty predicting the location of flow path on active alluvial fans, alluvial fan floods could be more dangerous than riverine floods. Utilizing the alluvial fan characteristics, the United States Federal Emergency Management Agency (FEMA) developed a method to assess the flood risk of alluvial fans. The FEMA guidelines allow for a number of delineation methodologies that include geomorphological method, one – and two- dimensional fixed-bed hydraulic modeling, and composite methods that combine engineering and geological approach. The United States Federal Emergency Management Agency (FEMA) used a simple stochastic model named FAN for this purpose, which has been practiced for many years. In fact, the first attempt to address the alluvial fan flood complexities was performed by Dawdy, who developed a probability- based model. The model was based on a mathematical formation that was developed after a series of catastrophic alluvial fan floods and debris flows in the 1970s. FEMA applied directly this approach directly in a number of alluvial fan flood plain delineation studies in the 1980s, and thereafter, the FAN model was developed. The FAN model is a DOS-based software package that uses Dawdy's basic equations as well as a modification proposed by DMA consulting Engineers to predict flow depths and velocities on alluvial fans, on a regular basis. Also, it has been found that geological and geomorphological data have great impact on estimation of alluvial fan flooding. To sum up, geological maps could be a powerful tool for better analyzing flood hazard on alluvial fan, due to incorporating the effects of erosion and sedimentation. In fact, using geomorphological analysis can provide a context for: (i) understanding the basic system process, (ii) realizing the past up to present, and (iii) calibrating or verifying hydraulic modeling results. The goal of this study was to examine the applicability of overlaying layers of land/ground susceptible to erosion, water erosion potential, and hydraulic flooding zones in alluvial fans with the least needed data. This study was conducted on a fan located in Iran using a combination of the FAN model, the hydraulic portion of the HEC-RAS, and geomorphological information. The Ferizy fan in Khorasan Province, which is located in arid regions in the eastern part of Iran, was considered for this study. In this paper, a new method is introduced and applied for each data layer and the results are discussed. Initial stages included three steps: (a) identifying the alluvial fans landforms, (b) determining the active and inactive areas of alluvial fans, and (c) delineating 100-year flood within these selected areas. This information was used as an input in the mentioned three approaches of the (i) HEC-RAS model, (ii) geomorphological method, and (iii) FAN model. In this study, three steps have been followed to achieve the goal: 1. The FAN model was established using the 100 year return period hydrograph and the average slope which was extracted from topographical maps; 2. The HEC-RAS model was executed by using the 100-year return period hydrograph and topographical maps; 3. Active and inactive areas were distinguished by considering topographical maps, field investigations and geologic data; 4. Thereafter, all the models, results, and field investigations were georeferenced and overlapped in GIS as separated layers and each layer was appointed a score using a scoring system; 5. Finally, the score of layers was multiplied and afterwards the pixels with the highest value and pixels with a score of 0 were considered to be the highest and the lowest hazard zones, respectively. Thereafter, the results of each model were obtained and geographical information (GIS) layers were created and overlaid. Afterwards, using a scoring system, the results were evaluated and compared. In this paper, a simple but effective solution to estimate flood hazard is proposed. The present approach suggests a combination of the FAN model, geomorphological approach and a simple portion of the hydraulic model of HEC-RAS. It was concluded that the integrated method proposed in this study is superior at projecting alluvial fan flood hazards with minimum required input data, simplicity, and affordability, which are considered the primary goals of such comprehensive studies. These advantages are more highlighted in underdeveloped and developing countries, which may well lack detailed data and financially cannot support such costly projects. Furthermore, such a highly cost-effective method could be greatly advantageous and pragmatic for developed countries.

Water and energy are the most important sources that have been faced with a serious crisis, over the last century. Iran is at risk according to lack of water resources and tenses. This country, among arid and semi- arid countries in the world, is facing with increasing of water demand due to population growth, urbanization and development of agricultural and industrial sections. The continued increase in amount of demand causes to increase the gap between supply and demand of water in the future. Therefore in such areas to avoid crisis situations, it is essential to manage water resources .Bandar Abbas city is located in desert environment of Hormozgan province, Iran. This city, because of the relatively low rainfall and the high coefficient of variation, has faced with the drinking and agricultural water crisis. In the other hand, because of the high population growth and development that has occurred in the recent years, demand to water resources has increased in Bandar Abbas, day by day. Bandar Abbas city, with average rainfall of 188 millimeter and high coefficient variance (C.V) rates, needs to be investigated from the aspect of suppling drinking water.The aim of this study is to prioritize drinking water resources in drought and normal conditions and eventually determining the best choices for drinking water source for Bandar Abbas city. Therefore, prioritize of water resources for efficient use in critical condition, can be an effective step. Decision making is essential in many fields to find the best approach. The aim of the present study is to prioritize the supply resources of drinking water in Bandar Abbas. In this study, identification of the affecting factors for prioritization has been done, using the TOPSIS model as one of the decision making models (AHP). To determine the best source of water, natural and human criteria was used. In this model, the first step was identifying and collecting data and calculating some factors that related to water resources, in the eleven region of Hormozgan province (surrounding Bandar Abbas). Based on the data obtained from selected regions, the intensity and importance of each area was defined by numbers. The next step was forming a decision tree with hierarchical structure. The tree was designed in descending order with three levels that contains of goal (areas priority), criteria and options (eleven areas around the city of Bandar Abbas), respectively from highest to lowest level. Then, the decision matrix was formed with quantitative criteria in the TOPSIS model. Afterward, six steps applied for assessment and calculation to gain the results. Thirty questionnaires were used to determine the weights of the criteria. The matrix which was based on the decision tree consisted of eleven rows and eighteen columns (based on eleven water resources and eighteen affecting parameters on priority in both normal and drought). Using different types of parameters in the matrix with various units and comparing their effects is an advantage for TOPSIS model. The 10 parameters used for prioritization in the matrix were included of: cost, social acceptance, unexpected pollution, water quality, vulnerability to floods and earthquakes, the camouflage, temperature, potential evaporation, distance from the city center and height from the sea level. Results showed that the most weights in normal and drought conditions were due to EC (0.08) and the cost of water production (0.06), respectively. While, the least weights, in the same conditions, were related to the parameters of resources heights from the sea level with 0.02 and 0.03. Results also showed that Esteghlal dam and Shamil Takht wells could be the best resources of drinking water, respectively, in normal and drought conditions, with the weights of 0.28 and 0.35, respectively. This is while in droughts in recent years, much of the drinking water of Bandar Abbas has been provided from the Minab dam and other has been supplied from Minab plain wells and Shamil Takht wells. It is suggested that same study perform applying another model in prioritizing and then the results compare with the current study. It is better to use more parameters such as hardness, evaporation and faults in the areas. Also it is recommended to use among coordinated subgroups and scoring reparative models in MADM and ELECTRE method for prioritizing drinking water. In these suggested methods, instead of ranking options a new concept known as non-ratings could be used, so that in this way ineffective options could be removed.

Changing the morphology of rivers, associated with erosion and sedimentation, has resulted in damaging riverside structures and loss of valuable agricultural lands. This process occurs in long length of rivers, which structural protection is virtually impossible due to high costs. Today, the use of bioengineering techniques (non-structural) is increasingly growing, due to economic and environmental sustainability. Lack of technical knowledge in biological characteristic of plant species is one of the important limitations of the bioengineering techniques in the protection of riversides. The matrix root and soil increase the soil shear resistance. The Wu (1976) model was employed to calculate the increase shear resistance. To apply this model, determination of the root tensile strength is required. The pilot of research was located 12 Km from Darashahr city, inside of Vahdatabad village, on the Seimareh riverbank, Ilam Province, Iran. Six trees (from Tamarix species) were randomly selected on the river bank by a distance about one km. The annual precipitation, temperature, evapotranspiration, relative humidity and wind speed in this region are 442 mm, 20.2 Cₒ, 1874.2 mm, 61.7% , 3.4 m/se and 122 m3/se, respectively. This zone is located in the semi-arid climate. The area of watershed is about 28.5 km2. Circle profile trenching method was employed to obtain characteristics of root system in direction of river flow and the riverbank slope. The trees were selected on the left riverbank. Circular trenches were dug at a distance of half a meter from the tree stem. The maximum depth of each tranches was 1.5 meters. Surface of the trenches were divided into four equal quadrants. To define the quadrants, X-axis was selected in the direction of flow and Y-axis in perpendicular to the river flow. Then, the quadrants were named in trigonometric direction. In this way, the first and second quarters were located on the upslope and the third and fourth quarters on the downslope. As well as, the second and third quarters were located in upstream and the first and fourth quarters in downstream. For testing tensile force, the sample roots were selected from each quadrant. The roots were cut in 20 cm length, and were kept in a solution of 15% alcohol. Before testing, root diameter in three points of the beginning, end and middle were measured. Using the arithmetic average diameter, cross-sectional areas of roots were calculated. Tensile force was applied on roots sample with 10 mm/m velocity. Root tensile strength was calculated through dividing the amount of tensile force at the moment of rupture (on the cross-section of root,) by the area (according to the mean root diameter). Hundred and forty eight root tensile tests were performed. Seventy three percent of them were successful. The main problem in these tests was the root slip and rupture in between the clamps. For the larger dimeter of roots likelihood of slipping is increasing. The minimum and maximum root diameters were tested, which were 1 and 8.2 mm. The minimum and maximum tensile forces were 16.1 and 1063 N. The relationship between the diameter and rupture force was a positive power function. Its coefficient of determination (R2) was equal to 0.92. In other words, by increasing the diameter of the root, the amount of force needed to rupture is increasing. In this way, the minimum and maximum root tensile strength was 6.1 and 44.7 MPa, respectively. The relationship between the diameter and tensile strength can be described as a negative power function. Its coefficient of determination (R2) was equal to 0.39. SPSS software was used for data analysis. Comparing the tensile strength of roots in the upstream and downstream slope and flow, Mann-Whitney and Kruskal-Wallis test were used. The result showed that average root tensile strength was not significantly different on the up and downslope and also by direction of the flow. Although the effect of flow and slope on root's tensile strength was slight, the effect of slope was more than flow. However, the average roots tensile for each tree was significantly different. The root tensile strength values decreased with diameter according to a negative power equation. In conclusion, the results suggest that it is likely the condition of environment and genetic characteristics of trees affects tensile strength. These findings may help to improve the application of soil bioengineering techniques in the protection of riverbanks.

Increasing the population and water demand for different uses and needs for accessing to the water resources with appropriate quality made the necessity to implement water quality management plans. Lack of attention to the quality of the released water from the dams can cause some problems and sometimes lead to irreversible damages on the environment. Therefore, the study of reservoir water quality, using field measurements or numerical modeling can be a key step in the operation of dam reservoirs. Nowadays, many models have been developed to simulate hydrodynamic and water quality of the water bodies. Among these models, CE-QUAL-W2, a two-dimensional width-averaged model, has been extensively used as a commercial model all around the world. Karun-3 dam is one of the double-arch concrete dams in the southwestern of Iran which was constructed on the Karun River, with 185 meters height, 462 meters crest length and 60 km lake length. The main goal of Karun-3 dam is to control the seasonal floods of Karun River, increase the potential of regulating water for drinking and agriculture uses, and also to produce hydropower. Considering the multiplicity of tools, features and structures used in the development of the model equations, the analytical methods and the quality conditions are needed for modeling and forecasting temperature changes in Karun 3 dam reservoir. In this study, the CE-QUAL-W2 model was selected for the thermal and chemical simulation. The required data to run the model can be divided into six categories: geometric data, initial conditions, boundary conditions, hydraulic parameters, kinetic parameters and calibration data. After inputting the bathymetry file, in a process of trial and error and by using the real elevation- area chart, the geometry of the reservoir was calibrated. Then the observed water surface level in the reservoir was compared with corresponding simulated water surface level data. After geometry and surface water calibration and making other input files, the quality stratification of the reservoir needed to be calibrated. Since this model included a large number of calibration coefficients and there is no standard guideline for this task, the model calibration is a time-consuming process. In this paper, first, the effective coefficients were identified by sensitivity analysis. Then, the calibration performed after classification of the coefficients. During sensitivity analysis of the different affecting parameters, it was found that wind sheltering coefficient in the region is more effective than other parameters. In the present study, the monthly data of Karun-3 dam reservoir measured from February until September of 2015 were used to construct the model. The results showed that this method was suitable for making accurate predictions of temperature stratification and reducing run time. The Absolute Mean Error (AME) for water surface elevation and bathymetry were obtained 0.74 m and 0.77m^3, respectively. Based on the obtained results, in the late February, the reservoir has full mixing and has a strong summer stratification that starts from April and peaked in mid-July. Afterwards by reducing the incoming radiation over the reservoir, stratification formed and goes into the mix. The water temperature in the reservoir was never less than 4 °C. Also, the considered reservoir is located in a tropical region and the temperature difference between Hypolimnion and Epilimnion was less than 1 °C in February; so the thermal stratification in the reservoir is not significant. Therefore, the reservoir can be considered full mixing during the winter. The trend of qualitative parameters also affected the thermal stratification. Variations of the dissolved oxygen also showed the decline of this parameter toward depth. So that in September the concentration of dissolved oxygen decreased from 7.07 to 4.37 milligram per liter. This decline intensifies in warmer water. So that the maximum amount of dissolved oxygen in Hypolimnion occurs in February and the lowest in September. Because the simulation process is not free of human error in sampling and analysis, full matching is impossible in this process. Therefore, equations in some cases have been simplified. The above mentioned limitations eventually are lead to differences between simulation and field data. The lowest values of root mean square error in the course of the simulation for temperature and dissolved oxygen were 4.82 °C and 1.73 milligram per liter, respectively, and for absolute mean error were obtained equal to 3.37 °C and 1.35 milligram per liter, respectively.

Increasing need for water in the arid areas of the world has resulted in the emergence of wastewater application for agriculture and landscape. The use of wastewater for irrigation is increasingly being considered as a technical solution to minimize soil degradation and to restore nutrient content of soils. Irrigation with wastewater due to nutrients in its composition caused to effect on soil, plant, and groundwater. Under irrigated agriculture, a certain amount of excess irrigation water is required to percolate through the root zone, so as to remove the salts which have accumulated as a result of evapotranspiration from the original irrigation water. Therefore, it is more necessary to manage water. Reuse of treated wastewater for turf irrigation is often viewed as a way to maximize existing urban water resources. This study was done at Islamic Azad university (Khorasgan branch)'s filed in summer, autumn and winter 2014. The soil of Islamic Azad university (Khorasgan branch)'s filed is classified in loamy texture. A factorial experiment plan was designed with 2 main treatments of irrigating system (Silica filter around emitter of subsurface drip irrigation (SDI) and Drip Irrigation (DI) methods) and two sub-treatments of irrigation water sources (irrigation with field water and wastewater of Khorasgan university with EC 6 dS/m). Also, 4 replications were considered in the plan that irrigated by 9 months. All analyses were done every three months by APHA methods. The results of soil analysis showed the OM% was low in both soil depths (0.2 % and 0.1% for surface soil (0-30 cm) and subsoil (30-60 cm), respectively). Also, the soil salinity was 8.91 and 7.78 dS/m for 0-30 and 30-60 cm of soil depths, respectively. Soil pH was neutral until moderate alkali (8.91 and 7.78 for the two soil depths). EC and pH in field water was about 4.19 dS/m and 7.01, respectively. Also, the wastewater that made by mixture of field water and leachate of Organic compost of Esfahan as second water irrigation had EC equal 6 dS/m. The wastewater quality was low. The concentration of all cations and anions was very high and upper than standard concentration, especially SO42-, Cl-, Na and Ca. The results show that irrigation with wastewater by passing time caused to significantly increase pH, OC, EC, SO42-, NO3-, PO3-, Cl-, Ca, Mg, Na and K, except HCO3- concentration in soil. Based on the results, the maximum concentration of N-NO3 was observed at subsoil, in opposit to the maximum concentration of N-NH4 which was at surface soil due to colloid absorption. On the other hand, the effect of depth of irrigation illustrated that all of the soil indexes except K, NO3, HCO3- and PO3- were significantly higher in surface soil than subsurface soil layer due to four factors: leaching, adsorption, organic complex and phosphate combination. The mean of interaction effect of time, depth, and kind of irrigation method has a significant difference at 1% on soil characteristics, except OM. Based on the results, the Silica filter application under SDI irrigation system caused to increase irrigation efficiency to remove more salts by surface adsorption mechanism and treatment of wastewater. The choice should depend on the origin and quantity of contamination anticipated in the system, as well as the size of the irrigation system. The based on the results, it seems particles of silica filter affectes removing cation and anions from wastewater. This study suggests that wastewater irrigation lead to beneficial changes in physico-chemical properties of the soil. It can be concluded that untreated wastewater can be used confidently in agricultural land, in the short term; while primary treated wastewater can be used in sustainable agriculture in long term. So, we recommend modifying the dose of irrigation, in order to reduce the quantity applied and to increase the frequency of application to avoid the loss of aggregation. We also suggest long-term studies to assess the feasibility of wastewater reuse because of a number of unanswered questions exist and still there is much room for development and work towards a more solid understanding of the actual consequences of the release of contaminant in the environment. The use of unconventional water sources (e.g. wastewater), as well as the use of high efficient irrigation systems (e.g. drip irrigation systems), has found special acceptability for management in agriculture.

Optimizing the economic utilization and saving of water resources is a global issue in water resources and its demand management. Also food demand continues to rise with increasing population. Thus, it is necessary to use water resources efficiently in the agricultural sector as the major consumer of water resources in Iran. In relation to economic assessment of agricultural water uses, especially wheat as a strategic and dominant crop pattern, there has been inadequate study in the country and inappropriate attention to this issue. In this regard, it is important to investigate different timing and amount of irrigation, and determine optimum option based on different indices like productivity of yield per unit of input. Therefore, the main aim of this study is to determine the optimal water use in different growth stages and economic assessing of treatments in Shahrekord region, Chaharmahal & Bakhtiari province, Iran. This experiment was conducted in complete block design in Chahartakhte research station, in Shahrekord with dry and cold climate. There are five irrigation treatments included E0, E1, E2, E3 and E4 with the irrigation depth of 100, 85, 70 and 55 percent of wheat evapotranspiration obtain from lysimeter. Crop growth stages were divided into six stages (T1, T2, T3, T4, T5, T6) including germination, tillering, stem elongation, flowering, milky and dough. Deficit irrigation and water stress was applied on only one step of growth season (as an example only T1) and other growth season periods were irrigated based on 100 percent of wheat evapotranspiration. In the current economic assessment study to achieve the best deficit management practices through partial budgeting, the cost ratio for each treatment, net profit, total productivity of water use and profitability in each of the treatments were determined, respecting the price of water and irrigation and other inputs. When the price of water is more than the profit from increased production by changing irrigation management, water and irrigation costs are equal and it is called as profit. After determining the price of water consumption as well as income and production costs, water productivity results and statistical tests were analyzed. SPSS and MSTAT-C statistical software was used for statistical analysis. Then, the best period and the best level of deficit irrigation for the production of wheat were determined and suggested as the optimal level and stage for deficit irrigation application. Investigation of the average cost showed that the maximum net profit was happened in treatments E3 during the tillering (40492 thousand Rials). According to results, the maximum cost ratio was 2.25, related to treatment E4 which was applied in the ripening stage. In general, all treatments have benefit-cost ratios greater than one. E4 treatments applied during the plant to achieve maximum economic efficiency (12.78 thousand cubic meter) and maximum productivity of irrigation water (1.58 kg per ha). According to mean comparison results, E2 treatments had maximum yield equal to 5.25 ton per ha and E4 treatment had minimum yield with 3.85 ton per ha. There was no linear relationship between yield reductions and reducing the irrigation water application. Comparing the average yield resulting from the application of deficit irrigation in different growth periods indicated the period T4 with the lowest yield (4.28 tons per hectare) was the most sensitive period to decreasing the irrigation water. The maximum gross income was gained by E2 (74127 thousand Rials) and the minimum by E4 (58080). The irrigation treatments cost had declining trend, E0 to E4. In all treatments benefit-cost ratio were greater than one. Applying deficit irrigation during the growing period (with the economic productivity of 1.17) is recommended. After it, the treatments of E3 and E4 (with economic productivity 1.09 and 1.01, respectively) and then applying deficit irrigation practices in growing period, T2 and T5 (tillering and pasty), by productivity of 1.049 and 1.092 are suggested. Achieving maximum yield and economic productivity, E2 treatment is recommended. In this treatment with 70% of evapotranspiration, the economic productivity was equal to 1.13; and by applying deficit irrigation during the growing period, the economic productivity was equal to 1.17. Finally, note that it is necessary to identify the critical periods of water stress and be aware of the relationship between crop yield and water use in irrigation. To achieve optimum production in wheat cultivation, efficient use of limited water resources is inevitable

recent long successive drought in the southern part of Iran including Fars province, necessitate the need for water resources management. The wide changes in climate variables in the daily, monthly and yearly scales show the relationship of these factors with the atmospheric and oceanic teleconnection patterns such as ENSO, Arctic Oscillation (AO), the Antarctic oscillation, North Atlantic Oscillation (NAO), Madden-Julian Oscillation (MJO) and …. Madden-Julian oscillation, Oceanic Remote Link phenomena and stable patterns are caused by general circulation of the atmosphere. This phenomenon is mainly detected by the release of east side of an area of strong convection with the intensification of rainfall over the Indian and Pacific Ocean. The positive anomalies of rainfall first started in some parts of east Africa and West Indian Ocean and then spread to the east. In many researches in this field, main focuses have been on the relationship between temporal and spatial distribution of precipitation with MJO event's status. However there has been less attention to influence of the MJO on runoff in the country. While the amount of runoff is one of the main components of the hydrological cycle and plays key role in water resources management, agricultural planning, optimal utilization of dams and etc. Here the main objective is studying the influence various phases of the MJO on rainfall and runoff of the rivers in the Fars province of Iran. The daily data of hydrometric stations of Doroodzan, Pol-Khan, Cham-Chit, Bvshigan, Chiti, and rain gauge station of Bvshigan, Chiti, Chamriz, Farashband, Sad-Abad and Gere-Bala of these rivers were collected from the Fars Regional Water Office. Here the stations which had at least twenty years data and had a minimum number of missing data are used. In this study, the focus has been on the critical period of Madden-Julian Oscillation in the rainy seasons (October to March) from 1975 to 2015.The daily MJO index from Bureau of Meteorology are used to select critical period of eight phases of the MJO with conditions as the magnitude of the MJO index remain larger than 1 and the similar phase for the MJO at least in five days. Also ANOVA test were used to study the significant effect of eight phases of the MJO on the amount of rainfall and runoff of the rain gauges and hydrometric stations. Then LSD test was used to compare the differences between averages of the each selected groups. Finally, deviation and percentage deviation from the mean value were used to quantify the impact of each phase on the precipitation and runoff. The results of ANOVA test for rain gauges stations in Sad Abad, Jere-Bala, Farashband, Bvshigan, Chiti and Chamriz stations showed that the null hypotheses (equality of rainfall means in MJO phases) is rejected, accordingly we can conclude that the impact of MJO on the rainfall of selected stations is significant. This test for hydrometric stations of Pol-Khan, Dorood-Zan, Cham-Chit, Chiti, Chamriz and Bvshigan showed the significant impact of Madden-Julian oscillation on the runoff of Fars Province Rivers, too. Here null hypothesis of equality mean of runoff in hydrometric stations is rejected and LSD test confirmed the significant differences between the mean values in eight phases of the MJO.The result obtained from the hydrometric stations of Chiti and Bvshigan showed that phase 8 and 5 of the MJO has greatest positive and negative impact on the runoff of the rivers respectively. In Doroodzan and Pol-Khan hydrometric stations, the greatest negative impact on runoff is seemed in phases 5 and 7 of the MJO. The analysis of rain gauge data of Bvshigan and Chiti showed most precipitation (relative the mean value) in the phase 8 of the MJO which indicate positive impact of this phase of madden-Julian oscillation on rainfall value. The most negative deviation from the meam value is seen in the Phases 3 and 4 of the MJO in the stations of Bvshigan, Sad-Abad and Chiti respectively which shows negative impact of the MJO. In Farashband station of Dalaki river, phases 7 and 8 had the greatest positive and negative impact respectively. Generally, statistical analysis showed that there is a significant difference between the mean of rainfall and runoff value in various phases of the MJO in the selected rain gauge and hydrometric stations. In summary the analysis of the results in the hydrometric stations showed that the phases 1 and 8 of the MJO have the greatest positive impact and the phase 5 has the greatest negative impact on rainfall. For rain gauge stations, the results showed that the phases 7 and 8 of the madden-Julian oscillation has the most positive impact on rainfall amount and the phases of 3 and 5 of this oscillation has the most negative impact. So it is reasonable that at first MJO causes to increase precipitation amount in south of Iran in phases 7 and 8 then in two later phases (8 and 1) the increase in runoff value is seemed because of existence a lag time to convert rainfall to runoff.

Drought, on the contrary to other natural events like floods, earthquake and storms, occurs as a creeping and hidden phenomenon. In other words, it takes weeks or months to detect drought. Planning and development of water resources systems under drought conditions requires estimation of joint and conditional probability of duration and intensity of drought. Copula functions, which can be used for joint analysis of two or more variables, calculate the correlation between these variables, too. It should be noted that for construction of joint distributions, there is no limitation in selection of marginal distributions. In this research, to monitor meteorological drought in Shahrood synoptic station, Iran, two drought characteristics (i. e. intensity and duration) were analyzed jointly by using historical precipitation records and also copula functions. The Shahrood synoptic station, located in Semnan province, Iran, has longitude of 54◦58' E, latitude of 36◦25' N and height of 1325 m above mean sea level. The Semnan province has a variety of climates (from hot and dry to Caspian type). Since the standardized precipitation index (SPI) is known as famous index in studying the droughts, therefore, monthly rainfall data were obtained for the period of 1951-2010 and monthly SPI values were used to characterize drought intensity and duration. Some mono-variate distribution functions were separately fitted on drought intensity and duration. As a result, marginal distributions of Gamma and exponential were used for statistical analysis of duration and intensity of droughts. Then, to do the joint analysis, five copula functions (Clayton, Plackett, Galambos, Gumbel-Huggard, and Frank), which are usually considered in hydrological studies, were fitted on the data and their performance was evaluated by such criteria as root mean square error (RMSE), Akaike information criterion (AIC) and Nash-Sutcliffe efficiency (NSE). Copulas are the functions which connect multivariate distribution functions to their one-dimensional marginal distribution functions. In this research, the best copula function was selected and its parameter was estimated by three methods of maximum log-likelihood (MLE), firefly algorithm (FF) and big bang-big crunch (BB-BC) algorithm. By using the selected copula function, the joint and conditional probability and return period of intensity and duration of drought were calculated. In this paper, bivariate analysis of intensity and duration of drought in Shahrood synoptic station, for statistical period of 1951-2010, was performed, using copula functions. The parameter of selected objective function was compared by three methods. The results showed that joint and conditional probabilities of drought occurrence for duration of 8 months and intensity of 6.92 are 0.0038 and 0.073, respectively. The return periods for these conditions are 1106.47 and 236.21 years. The obtained results revealed that among the studied copula functions, Galambos was the most appropriate for bivariate analysis of drought intensity and duration in Shahrood synoptic station. This function was selected because it had the highest maximum log-likelihood (-443.8199), the least root mean square error (0.0683), the least value of Akaike information criterion (889.6399) and the highest Nash-Sutcliffe efficiency (0.9347). To show the good fit of Galambos copula function on duration and intensity variables of drought, the graph of empirical copula function was drawn with respect to theoretical copula function (Galambos), based on three methods of MLE, FF and BB-BC. The results showed that the points on these graphs could be fitted by the 45-degree line. Among the three criteria that were used to evaluate the copula functions, the maximum log-likelihood criterion estimated the objective function (RMSE) equal to 0.0683. While, the parameters which were optimized by firefly algorithm and big bang-big crunch algorithm, estimated the objective function equal to 0.0409. Therefore, the intelligent algorithms (i.e. firefly and big bang-big crunch algorithms) gave better results and thus are recommended to minimize the objective function and evaluate the copula functions. One of the reasons for using two different intelligent algorithms for optimizing the objective function is to get reliable results in the optimization process. In general, it could be concluded that the gained information from application of copula functions and intelligent algorithms in this research could provide accurate description of drought in the studied region, before its happening. This kind of information is usable in water resources management. When a drought is happening, this analyzed information can reduce the cost of damages in the region.

Recently, nitrate concentration in water resources has become an environmental problem of widespread concern. Mainly, high nitrate concentration is attributed to anthropogenic activities, such as the discharge of urban, rural and industrial sewage, and the excessive use of animal and chemical fertilizers in agriculture. In this work, a model was built to simulate large-scale migration of nitrate in water resources. Simulating and recognizing nitrate migration leads to control and reduce the negative environmental effects of nitrate leakage and its contamination. In this study, the amount of nitrate entering into the groundwater of Asadabad Plain was estimated. Asadabad is located in 47°47' to 48°16' E and 34°35' to 34°52' N, Hamedan province, Iran. The mean elevation from sea levels is 165m. In this plain, groundwater reservoir is the main source of drinking water. Therefore, analyzing nitrate in groundwater is critical. Geological and hydrological data of the plain and especially the areas of absorption wells were gathered and used in MATLAB software for modeling. Then, in order to achieve the estimation, characteristics of the soil in the time zone were taken into account. Simplifying the model, it was assumed that there wasn’t any entrance of nitrate from surface runoff in to the wells. Due to informal questioning from city residents, the wells depth in the region was normally between 5 to 10 meters. Thus the wells depth was considered as 6 meters for modeling. According to the basic data from region, 5 people were defined as well users and 0.005 cubic meters per square meters as well inflow for each day. The soil texture was mostly silty and loam with the hydraulic conductivity of 6.93 meter per day. Also, infiltration rate was considered as 0.01 meter per day. The amount of and retardation coefficient determined as 1, which indicated high mobility of nitrate in the soil. The discharge rate of groundwater was considered as 0.0015 cubic meter per square meter per day. According to researches and data from the region, average nitrogen excretion per capita was 7.9 - 12.5 gr per day. A hybrid modeling approach was used to investigate the effect of nitrate produced from pit toilets and entered into the groundwater. This comprised an analytical solution for steady-state reactive transport through the unsaturated (or vadose) zone, which was then used as the input to a groundwater mixing model. To do this, the distance between the groundwater level and the bottom of the wells was calculated as an average of 40 meters. According to lack of accurate data of nitrate decay rate in soil and in order to better cover the results, the half-life of nitrate was considered as 500, 1000 and 1500 days. Hence, considering the distance from bottom of wells to the groundwater level and different time intervals (from 12 months to more than 50 years) and three half-lives, various amounts of nitrate concentration were calculated The results indicated the high probability of nitrate pollution at the groundwater level are higher than the global health standard for drinking around wells, over a period of 50 years, with a medium to long half-life. Considering the groundwater feed rate as 0.0015 cubic meters per square meter and the hydraulic gradient as 0.015 and the half-life of nitrate 500, 1000 and 1500 days, passing less than 50 years, the nitrate content in 18 meters depth will be 200 milligrams per liter,. Also, at a distance of about 40 meters from the groundwater level, the concentration of nitrate will reach 115 mg/L. At the same time, with a half-life of 1,500 days, this amount will reach about 398 mg/L, and in just five years nitrate levels will pass through this global standard. The results showed that after a short period of 50 years, for an aquifer located 40 meters from the floor of an absorptive well, the probability of increasing the concentration of nitrate for drinking water is to a level above the WHO. An approach such as frequent drainage of wells, accurate location, and distance from the aquifer level as well as well-positioned changes can reduce the penetration of nitrate into groundwater. Of course, the implementation of these approaches will be limited due to technical and social considerations as well as economic ones.

Mesopotamian Marshes are among the largest wetland areas in the world with an area of over 9,000 square kilometers. This area composed of three main wetlands that are named Central, Hawizeh and Hammar wetlands. Hawizeh Wetland (Hoor-Alazim Wetland in some publications) has an area of 3,000 square kilometers, which lies between 〖47〗^° 〖30〗^' and 〖48〗^°longitude, and 〖31〗^°and 〖31〗^° 〖50〗^' latitude. It is located between the end of the east delta branches of the Tigris and the end of the Karkheh River in the Iran-Iraq border. About one-third of this wetland is located in Iran which is known as Hoor-Alazim. In recent decades, by implementing multiple dam constructions and irrigation networks projects in Hawizeh Wetland basin and also wrong policies of the Ba'ath regime of Iraq in diversion of Tigris River, the Hawizeh Wetland is not in appropriate status. This wetland, once was controlling dust has become a source of dust which causes negative impacts on society, economic, environment and human health in affected areas, such as many southern provinces of Iran. The effect of dust storm is not limited to the inside of the region. In other words, it has cross-border impacts and so the cooperation between countries to deal with this problem and prevent its occurrence is necessary. The purpose of this research is evaluating and modeling of water resources in the downstream of Karkheh Dam (in Iran) and Tigris River (in Iraq and Turkey), using WEAP (Water Evaluation and Planning System) software. In this regard, various scenarios, such as development scenarios (A3, A2 and B2) and natural (no project) scenarios (A1, B1), were applied for the current and future (2042) conditions to assess the supply of environmental water demand for Hawizeh Wetland. To increase accuracy and reduce error of simulation, this model was calibrated and validated at two points. The first point was chosen on hydrometric station on Tigris and the second point was selected on four hydrometric stations (K3, K4, K5 and K6) which are located on tributaries of Karkheh River, near the Hawizeh Wetland. To simulate the Tigris River Basin, discharge of hydrometric station T1 in Faysh Khabur area (where the Tigris enters Iraq) with the volume of water use from the Tigris River and its tributaries in Turkey was considered as the headwater. Then the various water uses including agriculture, industry and drinking as well as runoff and streams were added to Tigris River model and the results were calibrated and validated in a hydrometric station. In order to estimate the amount of errors in calibration and validation of the simulation model, the Mean absolute relative error (MARE) was used. The calibration error in the first and second sections in the downstream of Karkheh Dam and the hydrometric station T8 in Tigris River basin were obtained as 0.055, 0.077 and 0.033, respectively. The results showed that the best way to restore Hawizeh Wetland is A1 and B1 scenarios, in which the environmental water demand is unsupplied with the index of 2.5% and 9%, respectively, in Karkheh and Tigris basins. Moreover, the worst state are A3 and B2 scenarios in which environmental water demand was unsupplied with indices of 45% and 33%, respectively, in the basins of Karkheh and Tigris. The value of indices in scenarios A3 and B2 demonstrate that if the current trend in water resources development in Tigris and Karkheh rivers be continued and a comprehensive water management plan is not performed for the basins, the Hawizeh Wetland will not be existed anymore in the future and it will become a source of dust storm. As a conclusion, the results also showed that not only in development scenarios A3 and B2, the wetlands environmental demand is not provided but also it happened in natural scenarios A1 and B1 with the indices of 2.5% and 9%, respectively. It is proved that if the effects of existing and planned development projects of irrigation, drainage and dams be ignored, there are still reasons such as unsuitable cropping patterns and use of traditional irrigation methods which are the obstacles for the supplying environmental water demand. Furthermore, with existing and planned development projects of irrigation, drainage and dams, Hawizeh Wetland undoubtedly will not occur any longer in the future and it will be converted to a source of dust storm.

Since there are a few reports available regarding the hydraulics of flap gates, it was aimed to conduct a research work on these kind of structures to make it clear whether they could be meet the desired advantages in flow measurement activities. Flap gates are made of cast iron or ductile iron, depending on the type of service. A small differential pressure on the back of the gate causes it to open automatically to allow discharge through levees, sewer lines or drainage conduits. When level of water on the face side of the gate rises above water level on the back side, the gate closes automatically to prevent backflow. Automatic drainage gates must be kept clean if they are to function correctly. The hinged flap acts as a natural skimmer to cause timber, logs or trash to catch between the flap and the seat at low flow. Periodic inspection and cleaning should be scheduled when the water flowing through the flap gate carries floating material. Flap gates provide a simple and cost-effective mechanism to maintain upstream water levels and flow measurement in small canals. Once installed and proper operation is verified, the gate only requires lubrication of its bearings and occasional painting for maintenance. It needs no electric power and no manual adjustment for varying flow rates. This gate can be used in open channels with rectangular section or circular section and ducts under pressure, for flood control, municipal projects, farm levees, sewer outfalls, industrial waste lines, water and sewage treatment plants, tidal drainage, irrigation systems and pump discharge control. In recent years, huge developments have been achieved on flow measurement. However, these achievements were faced with high installation and operational costs as well as highly trained human sources for their better utilization. Therefore, revision in traditional flow measuring tools is needed to get an acceptable precision and low cost of erection and operation. Present research covers the results of a theoretical and experimental investigation on a circular and quadratic flap gates which installed at the exit of a circular channel. Two individual circular pipes of zero slope and diameters of 200 mm and 300 mm were selected as water reach. All experiments were conducted in a circular plexiglas-walled fume, 5.7 m long, having a recirculation flow system. To measure the flow discharge, a sharp triangular weir with apex angle of 90˚ in the upstream of channel and the conveyor to measure the gate opening was used. In this study, the flap gate was tested with different weights. For circular Flap Gate Dimensionless weight (w/ (ρgD3)) varies from 0.0343 to 0.2542 and for square flap gates these values vary from 0.0562 to 0.3305. During tests dimensionless discharge for circular flap gate varies from 0.0123 to 0.2503 and for square flap gates these values vary from 0.010 to 0.258, As well as the circular gate opening which was in the range of 0.0123 to 0.4088 (radian)and for square flap gates these values were in the range of 0.0174 to 0.4012 (radian). The relevant theoretical equations were established to determine the flow discharge and then calibrated by using of experimental observations The research took the advantages of tentative method, basic equation of weir discharge and momentum principles. The values of maximum error (ME), mean absolute relative error (MARE) and root mean square error (RMSE) were computed and used for comparison. The resulting equations of different methods were calibrated and verified by using about 98 laboratory data for circular flap gate and 97 laboratory data for quadratic flap gate. In, basic equation of weir discharge mean absolute relative error for circular flap gate is equal to 4.41% and 5.55% for quadratic flap gate, this amount is in order for momentum principles 5.66% and 6.84%. A comparison of the values from the derived equation with statistical criteria demonstrated a high accuracy basic equation of weir discharge. It was shown that the proposed method would demonstrate high accuracy in estimating the flow discharge of the flap gates under free flow regime. The absolute relative error was ranging from 3.34 to 6.66 for circular gate, and 4.1 to 8.14 for quadratic flap gate. Advantage of theoretical equation in comparison regression equation is it can be used outside of experimental data but regression equation just has interpolation capability.

Water Distribution Systems (WDSs) are important and critical structures which transfer safe drinking water to consumers through network pipes. Today, intentional and accidental contaminant events can be considered as threat for public health of society. In this regard, water utility managers increasingly feel the need to detect the contamination. Contaminants can be injected at any times and locations. Therefore, continuous monitoring and investigating of water quality parameters cause increasing inherent safety of WDS against internal threat and deliberate attack. It should be noted that although monitoring all of the nodes is ideal in the network, it is not an economic method. So, optimal sensors placement is investigated as a cost-effective framework for reducing further damage of contamination events. Also, optimal designing of detection sensors reduces the network vulnerability through maximizing the probability of contamination detection and minimizing affected population. In the last decade, optimal placement of contamination detection sensors in water distribution systems was investigated in a large number of studies. Based on these strategic problems, confliction of interests and priorities among involved stakeholders can cause challenges. In this study, a multi-objective simulation-optimization model is developed based on the EPANET water quality simulation model and NSGA-II optimization. In this paper, deliberate contamination injection scenarios are generated using Monte-Carlo simulation model and simulated by EPANET water quality simulation model. It’s necessary to consider uncertainties in deliberate contamination injection to investigate WDS in critical conditions, including: mass of contamination, duration of injection, time of injection at a day and location of injection. The output data of EPANET was stored and used as input for multi-objective optimization model to obtain trade-off curve among utility functions of stakeholders. Storing all water quality matrix for single injection, considering affected population and detection time in database and then using them in optimization model provide a way to deal with the high volume of simulation data and reduce running time of the model. The aforementioned database was imported in the optimization model to obtain the optimum placement of the sensors among all injection scenarios with respect to utility functions. The main object of this paper is presenting an appropriate process to obtain optimal layout and number of detection sensors in WDS which should maximize the satisfaction of involved stakeholders. In this study, Water and Wastewater Company, National Disaster Management organization and Ministry of Health and Medical Education are the three main stakeholders in the optimization of number and location of sensors in WDS. For this propose, three utility functions, which are linear combinations of four objective functions, are assigned to the three stakeholders. The mentioned utility functions are equal to sum of weighted normalized objective functions which represent utility of stakeholders. These objective functions are the number of sensors, detection time, affected population and probability of undetected events. In the proposed methodology, layout and number of sensors not only integrate for obtaining water security goals, but also for satisfying stakeholders based on their utility function. Solving the NSGA-II optimization model results a trade-off curve among utility function of the involved stakeholders. Two approaches are utilized to determine a compromise solution on trade-off curve, including social choice theory and fallback bargaining method. According to the desirability of the objective function from stakeholders’ point of view, different weights allocated to objective functions. Then, Social Choice Theory and Fallback Bargaining Methods are applied to choose a point within the interaction curve which minimizes the conflict among stakeholders. Finally, based on the best compromise solution among all methods, 6 sensors are selected which scattered in water distribution system, properly. To evaluate the efficiency and applicability of the proposed methodology, it is applied to real-world WDS, Lamerd city, by arsenic injection as deliberate chemical contaminant injection. Based on the 6 selected sensors in Lamerd WDS, the values of affected population, detection time and probability of undetected events are equal to 4735 persons, 33 minutes and 13.6 percent, respectively. In this simulation-optimization model, injection scenarios are assumed to occur at only one node of WDS at a time. Therefore, future research should be considered in contamination injection from more nodes at one time or different times. It’s necessary to consider uncertainties in these deliberate contamination injections to investigate WDS in early and critical conditions, including mass of contamination, duration and time of injection at a day and location of injection.

Bottom outlets as the related structures play very important role in receiving water from reservoir and delivering it to downstream of dam. They involve with some undesirable phenomenon during operation period such as local vortices, intensive pressure fluctuation, cavitation, and control gate vibrations which consequently lead to reduce the coefficient of flow discharge and to harm outlet’s wall and control gates. It is necessary to appropriately understand the flow pattern in the bottom outlets, in order to identify and to decrease harmful effects. Seymareh dam is a concrete double-arch dams where located at 40 Km of Darreh Shahr, Ilam, Iran. The dam has two bottom outlets in body (No.1 and No. 2) in which the entrance levels are respectively 620 and 640 m above the sea level and 20 and 40 m above the river bed. The entrance of bottom outlets’ dimension is 17.85 * 9.56 m (height *width) and the emergence and service gate are respectively slider and radial. In the present research, pattern of flow has been investigated numerically by using FLOW 3D software, in No. 1 bottom outlet. This outlet has designed for maximum flow rate (654 m3/s) per 111.5 upstream water head and has 45.4 m length, so that on 100% service gate opening, the length of pipe flow is 36.5 m and free flow is 8.9 m. To simulate of flow’s hydraulic in FLOW 3D software, first the geometry of model has been prepared at Auto cad 3D in real size, then was called with stl format in FLOW3D software. Intended fluid in simulation is incompressible and single – phase and has been used K-ε (RNG) turbulence model because it has additional terms in k and ε transport equations. Also, time of the analysis was considered 30s. Out flow, wall and specified pressure condition respectively were used as boundary condition of outflow and walls of conduit and entrance condition which is supply reservoir head. In order to select the upstream reservoir dimensions (width, length) in the numerical model, the model has been performed with various dimensions on maximum head (111.5) and by checking of velocity profiles at different sections in conduit, 30*29.53 m were selected as reservoir dimension. The laboratorial results obtained from relevant physical model applied for verification of the numerical model performance. To verify of numerical model, the results of average pressure and flow discharge were used. For the parameter of average pressure per 30, 70 percent service gate opening and for the discharge parameter per: 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 percent gate opening in the normal head (100 meters), were validated. Good agreement with the results of numerical model and laboratory values indicate high ability of model to simulate flow field. The research results indicate that the flow velocity is gradually increasing on the flow direction while the flow pressure is reversely reducing. The flow velocity reaches to maximum 45.6 m/s and the flow pressure decreases to minimum -4.1 kPa when the bottom operates at normal head and complete service gate opening condition. The mean velocity and wall pressure between immediately upstream and downstream of the gate is sharply changed for small opening of gate. The maximum mean velocity of flow equal to 39.97 m/s (at 30% gate opening), and minimum mean wall pressure equal to 21.3 Pa (at 10% gate opening) are seen in the vicinity of service gate. For H /D < 1.2, the pipe flow in the bottom outlet changes to free surface flow condition. As result in the vertical sections, the uniform velocity and hydrostatic pressure distribution are observed approximately. The maximum velocity of flow equals to 8.4 m/s and the minimum wall pressure equals to 17.2 kPa. Also, the water surface profile varies rapidly due to expansion occurred on the flow section downstream of gate. By checking of longitudinal and lateral flow surface are observed longitudinal surface flow per smaller opening service gate, at the end of conduit is increasing because of located energy dissipation block. By increasing of gate opening, the effect of energy dissipation block decreased and flow surface profiles after passing the gate, take downward trend and per smaller gate opening lateral surface profiles have downward arc state. With increasing of gate opening, the process has changed and become to upward arc.

Infiltration is one of the most important parts of hydrologic cycle by which surface run off, groundwater recharge and design of irrigation systems can be linked. Numerous equations, some entirely empirical and others physically based, have been proposed over the years to express infiltration as a function of time. Among these equations, due to the simplicity and capability of fitting on most measured infiltration test data, the Kostiakov infiltration equation is widely used for design of irrigation systems. Influence of initial soil water content is not considered in this important equation. This study aims to investigate the effect of initial soil water content on empirical parameters of Kostiakov infiltration equation and to modify the equation based on influence of initial soil water content. In this research, two uniform sandy soils were prepared by passing a sandy soil through sieves. Following that, the two soil samples were dried at oven at 105 oC for 24 hr. Each dry soil sample was placed in a transparent acrylic cylinder with inner diameter of 7 cm and smoothly compacted by kicking a rubber hammer on cylinder body. After that, an initial water depth was placed on soil surface and falling head cumulative infiltration depth through the soil column was measured with the time. After diminishing of water level on soil surface, the humid soil column was drained by using a vacuum pomp. Then, the soil column water content was measured and the falling head infiltration test was repeated on the soil column. For two studied soil columns, falling head infiltration tests were conducted in three different values of initial soil water contents. To extend the experimental results to the field scale, a falling head infiltration test was also conducted on a clay textured field by using the double ring infiltrometers, with inner ring diameter of 25 cm, and outer ring diameter of 40 cm. Both the inner and outer rings were filled with the same initial water depth. Falling water level in inner ring was measured before water level would reach the soil surface. Simultaneously with last reading of water level, the two rings were pooled out and vertical distance from the soil surface to the wetting front was measured using an auger. Additionally, a steel cylinder was used and a soil sample with volume of 293 cm3 was taken from the vicinity of field test location and field initial soil water content was measured. For laboratory and field tests, wetness increment behind the wetting front was estimated by dividing the total infiltrated water through the soil by the depth of wetting front. The water content behind the wetting front of laboratory and field tests was also estimated by adding the wetness increment with initial water content. For laboratory and field tests, the Kostiakov infiltration equation is fitted on measured cumulative infiltration test data and empirical parameters of the equation are estimated for each test. Comparison between measured cumulative infiltration tests data of each laboratory soil column in different values of initial water contents indicated that water infiltration through the soil is strongly influenced by initial soil water content. With increasing initial soil water content, cumulative infiltration depth through the soil is significantly reduced. Additionally, laboratory results indicated that water content behind the wetting front of infiltration is a constant value and is not influenced by initial soil water content. Laboratory results indicated that the power of Kostiakov equation (b) is a constant value and is not influenced by initial soil water content, while the coefficient of equation (a) is strongly influenced by initial water content. With increasing initial soil water content, the a coefficient of Kostiakov equation is reduced. After analysis of experimental results, a coefficient of Kostiakov infiltration equation is related to the initial soil water content and the water content behind the wetting front of infiltration. Laboratory results were extended to the field scale. Based on laboratory results, the b coefficient of Kostiakov equation for the studied field was taken as a constant value. The obtained empirical equation for the a coefficient of Kostiakov equation was used and the a coefficient for the studied field was related to the initial soil water content and the water content behind the wetting front.